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        Attention and Working Memory Task- Load Dependent Activation Increase with Deactivation Decrease after Caffeine Ingestion

        Wei Peng,Jian Zhang,Da Chang,Zhuo-Wen Shen,Yuanqi Shang,Donghui Song,Qiu Ge,Xuchu Weng,Ze Wang 대한자기공명의과학회 2017 Investigative Magnetic Resonance Imaging Vol.21 No.4

        Purpose: Caffeine is the most widely consumed psychostimulant. It is often adopted as a tool to modulate brain activations in fMRI studies. However, its pharmaceutical effect on task-induced deactivation has not been fully examined in fMRI. Therefore, the purpose of this study was to examine the effect of caffeine on both activation and deactivation under sustained attention. Materials and Methods: Task fMRI was acquired from 26 caffeine naive healthy volunteers before and after taking caffeine pill (200 mg). Results: Statistical analysis showed an increase in cognition-load dependent task activation but a decrease in load dependent de-activation after caffeine ingestion. Increase of attention and memory task activation and its load-dependence suggest a beneficial effect of caffeine on the brain even though it has no overt behavior improvement. The reduction of deactivation by caffeine and its load-dependence indicate reduced facilitation from task-negative networks. Conclusion: Caffeine affects brain activity in a load-dependent manner accompanied by a disassociation between task-positive network and task-negative network.

      • SCISCIESCOPUS

        Vapour–liquid–solid growth of monolayer MoS<sub>2</sub> nanoribbons

        Li, Shisheng,Lin, Yung-Chang,Zhao, Wen,Wu, Jing,Wang, Zhuo,Hu, Zehua,Shen, Youde,Tang, Dai-Ming,Wang, Junyong,Zhang, Qi,Zhu, Hai,Chu, Leiqiang,Zhao, Weijie,Liu, Chang,Sun, Zhipei,Taniguchi, Takaaki,Os Nature Publishing Group UK 2018 Nature Materials Vol.17 No.6

        <P>Chemical vapour deposition of two-dimensional materials typically involves the conversion of vapour precursors to solid products in a vapour-solid-solid mode. Here, we report the vapour-liquid-solid growth of monolayer MoS2, yielding highly crystalline ribbons with a width of few tens to thousands of nanometres. This vapour-liquid-solid growth is triggered by the reaction between MoO3 and NaCl, which results in the formation of molten Na-Mo-O droplets. These droplets mediate the growth of MoS2 ribbons in the 'crawling mode' when saturated with sulfur. The locally well-defined orientations of the ribbons reveal the regular horizontal motion of the droplets during growth. Using atomic-resolution scanning transmission electron microscopy and second harmonic generation microscopy, we show that the ribbons are grown homoepitaxially on monolayer MoS2 with predominantly 2H-or 3R-type stacking. Our findings highlight the prospects for the controlled growth of atomically thin nano-structure arrays for nanoelectronic devices and the development of unique mixed-dimensional structures.</P>

      • KCI등재후보

        Attention and Working Memory Task-Load Dependent Activation Increase with Deactivation Decrease after Caffeine Ingestion

        Peng, Wei,Zhang, Jian,Chang, Da,Shen, Zhuo-Wen,Shang, Yuanqi,Song, Donghui,Ge, Qiu,Weng, Xuchu,Wang, Ze Korean Society of Magnetic Resonance in Medicine 2017 Investigative Magnetic Resonance Imaging Vol.21 No.4

        Purpose: Caffeine is the most widely consumed psychostimulant. It is often adopted as a tool to modulate brain activations in fMRI studies. However, its pharmaceutical effect on task-induced deactivation has not been fully examined in fMRI. Therefore, the purpose of this study was to examine the effect of caffeine on both activation and deactivation under sustained attention. Materials and Methods: Task fMRI was acquired from 26 caffeine naive healthy volunteers before and after taking caffeine pill (200 mg). Results: Statistical analysis showed an increase in cognition-load dependent task activation but a decrease in load dependent de-activation after caffeine ingestion. Increase of attention and memory task activation and its load-dependence suggest a beneficial effect of caffeine on the brain even though it has no overt behavior improvement. The reduction of deactivation by caffeine and its load-dependence indicate reduced facilitation from task-negative networks. Conclusion: Caffeine affects brain activity in a load-dependent manner accompanied by a disassociation between task-positive network and task-negative network.

      • KCI등재

        Impact of Liver Fibrosis and Fatty Liver on T1rho Measurements: A Prospective Study

        Shuangshuang Xie,Qing Li,Yue Cheng,Yu Zhang,Zhizheng Zhuo,Guiming Zhao,Wen Shen 대한영상의학회 2017 Korean Journal of Radiology Vol.18 No.6

        Objective: To investigate the liver T1rho values for detecting fibrosis, and the potential impact of fatty liver on T1rho measurements. Materials and Methods: This study included 18 healthy subjects, 18 patients with fatty liver, and 18 patients with liver fibrosis, who underwent T1rho MRI and mDIXON collections. Liver T1rho, proton density fat fraction (PDFF) and T2* values were measured and compared among the three groups. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the T1rho values for detecting liver fibrosis. Liver T1rho values were correlated with PDFF, T2* values and clinical data. Results: Liver T1rho and PDFF values were significantly different (p < 0.001), whereas the T2* (p = 0.766) values were similar, among the three groups. Mean liver T1rho values in the fibrotic group (52.6 ± 6.8 ms) were significantly higher than those of healthy subjects (44.9 ± 2.8 ms, p < 0.001) and fatty liver group (45.0 ± 3.5 ms, p < 0.001). Mean liver T1rho values were similar between healthy subjects and fatty liver group (p = 0.999). PDFF values in the fatty liver group (16.07 ± 10.59%) were significantly higher than those of healthy subjects (1.43 ± 1.36%, p < 0.001) and fibrosis group (1.07 ± 1.06%, p < 0.001). PDFF values were similar in healthy subjects and fibrosis group (p = 0.984). Mean T1rho values performed well to detect fibrosis at a threshold of 49.5 ms (area under the ROC curve, 0.855), had a moderate correlation with liver stiffness (r = 0.671, p = 0.012), and no correlation with PDFF, T2* values, subject age, or body mass index (p > 0.05). Conclusion: T1rho MRI is useful for noninvasive detection of liver fibrosis, and may not be affected with the presence of fatty liver.

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